Foods that are genetically modified have had their DNA structure changed, with a goal of improving the organism. This might make it more resistant to herbicides, so that it can grow while weeds around it are treated.

However, several studies have shown a potential connection between genetically modified foods and illnesses such as cancer, infertility, and severe allergies. But the health risks are not entirely clear: many of these studies were conducted on animals, and the results might be different for people. While European countries are banning GM foods, at the same time their researchers are encouraging the technologies. In the U.S., labeling genetically modified foods has become a hot political topic, even though there are no long-term studies on GMOs because they are relatively new to our food stream. Concerned? Read on.

2. Genetically modified soy and corn are probably in many of the foods you buy.

About 90 percent of the country's soy and corn crops are genetically modified. Since almost all processed foods contain their derivatives—and corn, the nation's largest crop, is a staple for animal feed—chances are high that you are eating genetically modified foods. How can you tell? For now, there are no labels required as there are in countries like Britain. Look for ingredients like maltodextrin,
high fructose corn syrup (HFCS), dextrose, soy lecithin, and corn starch. And unless your meat is grass-fed and specifically GMO-free, it's likely to have been affected, too.

3. It's not just plants; animals are being genetically engineered, too.

The AquAdvantage salmon is a genetically engineered fish that grows to maturity in half the time of its natural cousins (one and a half years compared to three), and the company behind it is in the final stages of the lengthy, FDA-required New Animal Drug Application (NADA). If approved, it will be the first genetically modified animal in the U.S. food supply.

This isn't the first time scientists have played with animals' genomes; the University of Guelph created the Enviropig, aka "frankenswine," in an effort to help pigs' digestion. But those GM pigs were subsequently killed off when the project lost funding.

In addition to corn and soy, other foods that have been approved for genetic modification in the U.S. include canola oil and animal products like milk, eggs, and meats. Also on the list: sugar beets, papaya, alfalfa, zucchini, and yellow squash.

5. You can decode how your food was grown by checking its produce sticker.

Codes starting with "9" are organic. Codes starting with "4" mean the food was likely treated chemically with an herbicide, pesticide, or both. Although codes starting with "8" are meant to designate genetic modification, most supermarkets have not adapted that labeling practice with their produce, so it's best to ask. Examples: Organic - 973634, Conventional - 450801.

6. Remember: organic food can still have traces of GMOs.

"Though organic rules prohibit the 'use' of genetic modification in organic
agriculture...if pollen blows from genetically modified corn into
your organic cornfield and pollinates a few kernels, you aren't 'using'
it — at least according to the USDA's interpretation
of those rules. In fact, some of the organic corn that's fed to
organically raised chickens or pigs, does contain a small level of GMOs," explains NPR. Also: Organic largely means the type of farming methods involved, i.e., no chemicals or synthetic additives. Organic farmers try their best to avoid contamination, but especially for crops like corn and soy, it can be particularly difficult.

7. You can check for the Non-GMO Project Verification logo.

This non-profit organization is currently the only third-party verification, offering a Non-GMO Shopping Guide and app. However, rising in popularity are retailers like Whole Foods, which recently became the first supermarket in America to require labeling on any GM foods. Also in January, high-level executives from some of the U.S.’s largest food corporations like Wal-Mart, General Mills, Pepsi-Frito Lay, Mars, Coca-Cola, and others met with the FDA to review a mandatory federal GMO labeling law.